1. Field of the Invention
The present invention relates to information handling systems and more particularly to quick conditioning memory backup battery.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
It is known to provide backup power to an information handling system via a battery pack. For example with the PowerEdge Expandable redundant array of inexpensive disks (RAID) Controller (PERC) available from Dell, Inc., a battery pack is used to backup memory, (such as a dirty cache memory located on PERC expansion card) when AC power is lost. One issue relating to the battery pack is related to gas gauge accumulated errors over time or cell failure. Due to this issue, it is often necessary to perform a learning cycle during which the battery is fully discharged to 3V and recharged again. The remaining capacity of the battery pack reported by the gas gauge is monitored by the RAID firmware (FW). In certain PERC systems, if the capacity of the battery pack drops below a certain threshold such as a 40% relative state of charge (RSOC) threshold, the firmware switches the write-cache policy of the system to a Write-through cache policy. The threshold may be selected based upon certain performance considerations (e.g., the threshold may be based upon a battery pack capacity needed to protect the cache memory for twenty-four hours). When the capacity rises above the threshold, the firmware re-enables a Write-back cache policy.
There are a number of issues relating to battery pack capacity. For example, during the learning cycle, the performance of the system can be negatively affected as the write cache policy is changed to write-through once the battery capacity is below a certain threshold, e.g. 40% RSOC, in this case. The learning cycle window is generally predictable, but can be bigger depending on the temperature in the system. For example, in certain systems, logic in the battery pack will not allow a charge if the temperate reaches or surpasses 65 C. Also, because of cell degradation, a certain threshold that is identified during the design of the system may not be not enough to meet the minimum capacity requirement to protect the data in cache memory for up to twenty-four hours.
For example, FIG. 1, labeled Prior Art, shows a conditioning cycle for a battery pack used with a PERC system. The capacity of the battery pack degrades over time. Additionally, the performance of the PERC system is degraded, as indicated by the diagonal lines, due to the unavailability of the battery pack for memory backup.